int dir[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
class Solution {
public:
   int shortestDistance(vector<vector<int>>& grid) {
      int ret = INT_MAX;
      int n = grid.size();
      int m = grid[0].size();
      int numberOfOnes = 0;
      vector < vector <int> > dist(n, vector <int>(m));
      vector < vector <int> > reach(n, vector <int>(m));
      for(int i = 0; i < n; i++){
         for(int j = 0; j < m; j++){
            if(grid[i][j] == 1){
               numberOfOnes++;
               queue < pair <int, int> > q;
               q.push({i, j});
               set < pair <int, int> > visited;
               for(int lvl = 1; !q.empty(); lvl++){
                  int sz = q.size();
                  while(sz--){
                     pair <int, int> curr = q.front();
                     q.pop();
                     int x = curr.first;
                     int y = curr.second;
                     for(int k = 0; k < 4; k++){
                        int nx = x + dir[k][0];
                        int ny = y + dir[k][1];
                        if(nx < 0 || ny < 0 || nx >= n || ny >= m || visited.count({nx, ny}) || grid[nx][ny] != 0) continue;
                        visited.insert({nx, ny});
                        dist[nx][ny] += lvl;
                        reach[nx][ny]++;
                        q.push({nx, ny});
                     }
                  }
               }
            }
         }
      }
      for(int i = 0; i < n; i++){
         for(int j = 0; j < m; j++){
            if(grid[i][j] == 0 && reach[i][j] == numberOfOnes){
               ret = min(ret, dist[i][j]);
            }
         }
      }
      return ret == INT_MAX ? -1 : ret;
   }
};

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}